Analytic instruments are used in a number of applications to quantitatively and/or qualitatively analyze a sample of interest. Analytic instruments are often found in laboratories and are sometimes employed within processing operations. As used herein, an analytic instrument is any device, system or arrangement that is able to receive a sample of interest and provide an indication of some aspect of the sample of interest. Analytic instruments include, without limitation, process gas analyzers, NO/NOx analyzers, hydrocarbon analyzers, continuous emission monitoring systems and process gas chromatographs.
A variety of analytic instruments employ regulated flows and a number of flow paths in order to provide analyses regarding various chemicals in processing or analytic contexts. The analytic instruments typically function using one or more flow devices that can initiate, interrupt, and reverse flow through the device. Such variety of flow functions is usually provided by a combination of one or more flow valves and/or pumps. In order to function effectively, analytic instruments will generally include a plurality of sample flow paths. In the context of a gas chromatograph, a number of flow paths are used to introduce a flow of sample and carrier gas into the gas chromatograph; flow a controlled amount of sample across a sorbent column; reverse the flow to elute the sample from the column; and detect the various components in the flow stream.
Gas chromatographs generally use pneumatic multiport valves to switch the flow of gas during analysis. These valves are critical to establishing a flow which allows the gasses to be separated. Among other things, it is very important that the gasses be able to enter and exit the valve with low leakage. This has been accomplished in the past through tube fitting connections or other various means. It is common for multiport flow selector valves to have 6 or even 10 individual ports, in addition to the actuation gas ports required for pneumatic actuation. A gas chromatograph may employ a number of such multiport selector valves. Accordingly, the time required to couple each tube to its respective port can add up to significant assembly time. Further, each individual tube connection is subject to variations in operator torque, tubing modifications, such as bending or routing, et cetera.
As the art of process analytic devices has progressed, there is increasing pressure to provide a lower-cost, higher-performance analytic instrument.